The present invention relates to heat dissipating structures and techniques and more particularly to a heatsink assembly for coupling and dissipating heat from a printed circuit through its mounting bracket.
In current high technology electronic apparatus, much of the circuitry is being provided by individual printed circuit boards constructed to accomplish a particular purpose and configured to be easily mounted and removed from the electronic apparatus. Each of the circuit boards includes a plurality of electronic components interconnected through terminals and conductive patterns on the printed circuit board to produce a desired circuit. As the complexity of the devices has increased, so have the circuits and number of components required to produce specific functions. Along with the increase in the number of components and the complexity of the circuits, the heat generated due to the increased power requirements has also increased. Because of the trend toward reduced size and limited space in which to mount the printed circuits, problems have arisen because of the inability to properly dissipate heat and maintain the components in a controlled temperature environment for extended life and reliability of operation.
A variety of techniques have been proposed to overcome the problems associated with increased heat generation. One such known technique employs individually screened and photoetched pads on one side of a particular electronic module to produce heat sinking areas similar in configuration to those circuit areas on an opposite side of that module. The pads are first formed and then dimensioned by solder-dipping or any other process capable of increasing the size and configuration of the heat dissipating pads. While improvements in heat dissipation may be obtained, the processes required to form the heat sinking areas are complex and still result in heat dissipation primarily by air convection at an inefficient rate.
In still other techniques, thermally conductive pads are molded to fit over the electronic components on individual printed circuit boards and maintained in contact with those components to thermally conduct heat away from the printed circuit board. In such structures, the pad is formed separately to have recesses similar in configuration to the components secured to the printed circuit board and is subsequently attached to the individual board prior to its mounting and coupling in the electronic apparatus. A heatsink is then positioned adjacent and in thermal contact with the thermal pad to conduct heat generated by the electronic components from the electronic apparatus. While this may again provide improved heat dissipation, the thermal pad is cumbersome, takes up a relatively large area, and must be maintained in a specific and aligned relationship with respect to the structure used to carry away the heat.
In still another example of prior art techniques, the circuit board itself is constructed so that the conductive areas interconnecting the terminals to which the electronic components are attached are themselves increased in surface area. The increased surface area of those conductive areas carries away the heat generated by electrical currents or heat absorbed from the electronic components. Alternatively, a conductive plate may be positioned on the side of the printed circuit board opposite to that containing the conductive areas and in contact therewith. In such an instance, non-conductive areas are formed on the surface of the conductive plate in contact with the printed circuit board to prevent electrical shorting at the terminal areas. In either case, heat dissipation is still primarily provided by air convection which is a relatively inefficient technique, especially in view of the surface areas involved in the printed circuit board.
In each of the above instances, the special structures required prohibit the formation of a printed circuit board and heatsink assembly which may be mounted in a variety of units in such a way that the printed circuit boards may be readily changed yet still provide efficient heat dissipation. There is therefore a need to provide an assembly and structure which will allow simplified mounting of printed circuit assemblies so that heat may be conducted away from the area of the printed circuit board to allow heat dissipation in areas other than adjacent the circuit boards or components themselves. There is also a further need for assemblies and structures which are capable of allowing easy insertion and removal of the printed circuit assemblies to facilitate easy repair and replacement of electronic circuits and components during operation of an electronic apparatus.
Accordingly, the present invention has been developed to overcome the specific shortcomings of the above known and similar techniques and to provide a printed circuit heatsink assembly which provides improved heat dissipation in crowded circuit environments.